The present invention relates to a magnetic separator that is especially adapted to separate plate-like metal objects such as metal can lids, also known as “closures” or “ends”.
Closures for metal beverage containers are generally of a circular shape with a flanged perimeter called a curl. The closures, or ends, are usually made of aluminum or steel, and the curl is used in attaching the end to a can body through a seaming operation. To aid the integrity of the seal thus formed between the can body and the end, it is a common practice to apply a bead of sealant or adhesive (“compound”) within the curl during manufacture of the end. Different types of coatings are also selectively or generally applied to can ends and can bodies for various other purposes as well, for example, to repair damaged coatings. For the purposes of the present description, coatings, sealants and adhesives are all considered to be “liquids” applied to a workpiece.
It is necessary in this manufacturing operation to cure or dry such liquids. It is known to dry can ends by infrared radiation, convection heating, or induction heating.
An induction heater, for example, typically includes a cabinet that supports a tube extending generally horizontally across the cabinet from one end to the other. An induction coil is wrapped around the tube. The ends move through the tube in a stacked relationship, that is, with abutting face-to-face contact with each other. When a suitable current is passed through the coil, the metal can ends are inductively heated. The heat is transferred to the compound on the can ends by conduction. The compound is heated and water is driven off from the compound into the surrounding air.
When the can ends exit the dryer, the compound on the can ends is substantially dry. A small amount of moisture may still be present in the compound, however. In addition, the can ends exit the dryer in a condition stacked adjacent each other (in a “stick”). Therefore, it is known to provide a magnetic separator at the outlet end of the dryer. The separator separates the can ends from each other by a small space, for example, one quarter inch. This separation facilitates final drying of the compound on the can ends. This separation also facilitates the grabbing of the can ends individually by a rotating wheel at the outlet end of the separator, as is necessary for further use and processing of the can ends.
The stick of ends coming into the inlet end of the separator may include some ends that stick up from the others. In some prior art separators, this can cause jamming or other problems.
The can ends are guided through the separator by upper and lower guide members that are solid metal pieces and therefore block the view of the pole plates. This can make it more difficult to adjust accurately the position of the pole plates, which determines magnetic strength.
In the prior art separator, the steps needed to adjust the vertical positions of the guide plates and the pole pieces can be tedious and may need to be repeated to set the adjustment properly. In addition, the upper guide plate is not easily removable to gain access to areas of the separator.